I might as well mention bk-7.2ce which is the first open-source release.

Release notes relative to bk-7.1

Release notes for BitKeeper version 7.2ce released May 9 2016
This is the first open source release of BitKeeper. Many changes involve
removing the licensing code.
Changes:
Upgraded TCL/Tk to v8.6 which improved appearance on MacOS.
BitKeeper now uses gfile pathnames in many places where sfile
pathnames were used in the past. The biggest change is that 'bk -r'
returns dir/file instead of dir/SCCS/s.file. Also many error
messages avoid printing SCCS/s.file pathnames since those are
confusing.
The code now uses PCRE for regex code everywhere. This mainly
changes 'bk changes -/regex/' and 'bk log -/regex/'.
Removed old commands:
bk _eula
bk lease
bk legal
bk more
bk status --compat
bk users
Several performance issues related to repositories containing
abnormally large numbers of tags have been fixed.
The BK/Web service has been given significant improvements to upgrade
the appearance from 1998 web standards. ;-)
Changes in individual commands
bk changes
New --lattice && --longest options to change selections based on
the input range.
New --json option to format output for web apps
bk delta
if the last line has no newline at the end and has carriage
returns, they will now be stripped. If no data is left, then the
line is ignored.
The -D option is now limited to RCS diffs. RCS diffs used to not
recognize no newline diffs. They are recognized now.
bk describe
New command to give a friendly name for the current cset like
bk-7.1+183@0x56d9f3c0 (last tag + # of csets since @ time_t of tip)
# Show the tip (and any other csets with that time stamp)
bk changes -c0x56d9f3c0
bk diffs
-h no longer prints a blank first line.
bk fast-export
Add --standalone mode for exporting single components from a
nested collection.
Add support for incremental exports to allow a git repository to
track a bk master.
bk rmgone
Rmgone was completely rewritten and removed a number of bugs and
shortcomings. The new code is nested aware, has a more
understandable output, and won't incorrectly remove some files.
bk makepatch
Makepatch now ONLY generates the bk-5.0 fastpatch format and
later. This breaks pull/push compatibility with bk-4.x, but old
repositories can still be cloned and read. bk clone --upgrade
is your friend.
bk upgrade
Now downloads new versions from the www.bitkeeper.org/downloads area.
This is also used to find the latest release as mentioned by
'bk version'.
Bugs fixed:
Fixed 'bk citool' support for pre-delta triggers. The old behavior
was terrible. (sorry)
'bk changes -R URL' with a bad URL could coredump. Fixed.
'bk chmod' could coredump when run outside a repository.